Brief analysis on dynamic charging technology of e

2022-08-16
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Charging while driving? Brief analysis of dynamic charging technology of electric vehicles

charging is like a bug for electric vehicles. If one day, electric vehicles get rid of the shackles of charging piles and don't need to look for charging piles everywhere, charging is more convenient than refueling

see here, everyone should understand the topic to be discussed today, wireless charging. However, unlike wireless charging in parking spaces, today we are going to discuss the technology of charging while driving. Of course, it also has a very academic name, which is called electric vehicle dynamic charging (DEVC) technology

imagine that electric cars don't need to be charged deliberately. They can be charged on the road every day, which brings many benefits. First of all, you can "reduce the load" on the battery, because you can charge the car anytime and anywhere, so a large capacity battery is not necessary, and the load of the vehicle also decreases

secondly, there is no need to wait for charging. Now electric vehicle charging is always unable to be as convenient as gasoline vehicle refueling, while wireless charging can be charged while driving, reducing the time cost. Finally, it solved the problem of the 3D industry authority report in the endurance. The endurance mileage of electric vehicles has been extended wirelessly, and the mileage anxiety problem does not exist

sounds quite fantastic? In fact, theoretically speaking, it is not difficult to implement. Let's first understand its principle

I. what's the matter with wireless charging

let's start with wireless charging. We know that wireless charging depends on current and magnetic field. Electricity and magnetism, the two lovers of CP, are killing each other. The pressure testing machine of Jinan experimental machine factory is mainly used in building engineering materials, and they often do things together

in 1819, Danish scientist Auster observed that if there was an electric current on a wire, a magnetic field would be generated around it. Later, it was found that the magnetic field generated by surrounding the wire in a ring or even winding it into a coil will be stronger and more concentrated, which is called current magnetic effect

In 1831, Faraday found that if a magnet or other magnetic field source is close to a coil without current, induced current will be generated on the coil, which is called electromagnetic induction

so how to make electricity and magnetism work together to output current stably

we need two coils. If one coil is powered on, there will be a magnetic field around the coil; Then we lean the other coil over, and this coil will have current. When the current is directed into the battery, wireless charging can be completed

when applied to the automotive field, this is electromagnetic induction wireless charging

we apply alternating current to the coil located on the ground. With the change of the magnitude and direction of the current, the strength and direction of the magnetic field around the coil continue to change, forming an interactive magnetic field. At this time, the coil of the vehicle chassis is in a constantly changing magnetic field, and an interactive current will be generated inside the coil, which will be rectified by a series of circuits to charge the battery

second, wireless charging driven out of obsessive-compulsive disorder

electromagnetic induction wireless charging is a technology that major automobile companies prefer to adopt in the early stage of wireless charging research

Mercedes Benz, Audi, Volvo and other car companies have developed a number of electromagnetic induction wireless charging models

there will be something like a mat on the parking lot. In fact, it is a primary coil used to generate a magnetic field. The vehicle chassis that can be used for wireless charging will also have a coil, which we call the secondary coil, to generate current

however, electromagnetic induction wireless charging has a big drawback, that is, distance. If this technology wants to generate current, the two coils must be "closely matched" to each other. Once there is a deviation, the current will not be generated

therefore, such technology often needs to be matched with accurate automatic parking technology to make the vehicle stop right above the wireless charging pad

sounds troublesome, doesn't it? This is to make everyone become Virgo and strengthen the rhythm of obsessive-compulsive disorder

therefore, scientists studied another wireless charging technology, that is, magnetic resonance wireless charging. We know that when two objects adopt the same vibration frequency, or resonate at a specific frequency, they can exchange energy with each other

magnetic resonance is that the primary coil generates a magnetic field that vibrates at a fixed frequency, that is, the resonant magnetic field, and then makes the vibration frequency of the secondary coil magnetic field the same, generating resonance, and finally realizing energy transfer

in 2007, the MIT research team successfully lit a 60W bulb 2m away through an electromagnetic resonator

in the automotive field, Toyota made an experiment in 2012, adding a secondary coil that can vibrate at a certain frequency to a plug-in hybrid Prius. There is a resonant magnetic field on the parking lot. When they all vibrate at the same frequency, they are used for the manufacture of car windows, and the secondary coil can convert the current of the resonant magnetic field

the output power of this wireless power supply system is 2kW. The frequency band used is 85khz, which is internationally recognized, and the power transmission efficiency is about 80%

in this verification experiment, the distance between the resonant magnetic field on the ground and the secondary coil at the bottom of the vehicle is about 15cm. The maximum allowable range of horizontal dislocation is the width of a tire (about 20cm)

Qualcomm has also launched a wireless charging system called halo, but it also stays in static wireless charging

the magnetic resonance effect is used to realize the energy transmission between the ground charging pad and the electric vehicle charging board. The power of this charging system can reach 20kW, and it takes about 5h to fill the 85kwh Tesla Model s p85 battery pack

third, let the electric vehicle move

if the charging pad or resonant magnetic field is placed on the road, the vehicle can realize charging while running, and bid farewell to the charging pile from now on

windows, which focuses on graphics, entertainment and networking, is too burdensome. In May this year, Qualcomm completed a dynamic wireless charging road test using a Renault all electric Kangoo van in Paris

two electric vehicles drove on this 100m long road at different speeds and completed charging at the same time. During the test, the Kango test vehicle has a speed of 100km/h and a maximum charging power of 20kW

the 100m road test built by Qualcomm includes four energy supply units, each of which is responsible for the power supply of the 25m road. At the same time, every 25m long energy segment has 14 sub modules, including coils and energy conversion circuits

as for the cost, a study by Renault, Electricite de France and the Northern Highway Company of France pointed out that the cost of building dynamic charging roads is 4million euros/km (two lanes), which can be said to be quite expensive

it seems that such a "golden" road can only be popularized on bus lanes first. In South Korea, the Korean Academy of science and Technology (KAIST) has built a 12km long dynamic charging road at the railway station in kuwei city in the south. The electric bus running on it uses magnetic resonance to realize wireless charging

having said that abroad, our country's research on wireless dynamic charging is not lagging behind. ZTE is well-known. At present, it has launched the test of wireless charging demonstration lines in Chongqing, Hubei and other places

wireless dynamic charging is still in the research state, and there is still a long way to go before it is popularized in a large area. Just think about it, there are a lot of problems that have not been solved, such as whether the compatibility of vehicles is consistent, whether the road is open or closed, and whether the current of the road can load multiple vehicles for charging? In addition, there is road monitoring and maintenance

these are all obstacles to wireless dynamic charging, but technology is always developing. Believe in the power of technology, the problem of charging will always be solved. Charging an electric car while driving is definitely not a dream

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